I'm confused. An exam question, " Suppose you have human cells growing in culture. You give these cells exactly 100 glucose molecules, suck out the ambient oxygen and place the cells in an anaerobic chamber. How many ATP molecules will be produced by these cells?"Answers:a. 100b. 200c. 400d. 3400e. 3600

I know that the process of Glycolysis produces 2 ATP (from the pyruvate - I think I'm not sure). My professor told us in lecture that pyruvate produces 36-38 when O2 is plentiful(aerobic respiration). 3-35 ATP when O2 is toxic(anaerobic respiration). And 2 ATP when O2 is limited. I figured it was 200 ATP because 2x100 but another peer of mine had said it was 400. Just trying to clear things up, any help would be appreciated.

well, since they give only round hundreds, they are not interested in partiall pathways (like if half of the pyruvate was degraded before it was stopped due to lack of NAD+ and FAD:)Glycolysis will definitelly take part. Probably also the pyruvate decarboxylation. However, the TCA cycle is questionable, because with 100 molecules I'd say the concentration of NADH will not be so high to stop it. But it's an exam question,so they probably want to know, whether you know that TCA runs aerobically only, althoughit doesn't require oxygen per se.Thus it's 200 ATPs from glycolysis (2 per 1 Glc) and could be additional 200 from TCA (1 per 1 acetyl-CoA).

JackBean wrote:well, since they give only round hundreds, they are not interested in partiall pathways (like if half of the pyruvate was degraded before it was stopped due to lack of NAD+ and FAD:)Glycolysis will definitelly take part. Probably also the pyruvate decarboxylation. However, the TCA cycle is questionable, because with 100 molecules I'd say the concentration of NADH will not be so high to stop it. But it's an exam question,so they probably want to know, whether you know that TCA runs aerobically only, althoughit doesn't require oxygen per se.Thus it's 200 ATPs from glycolysis (2 per 1 Glc) and could be additional 200 from TCA (1 per 1 acetyl-CoA).

The TCA or Krebs cycle only occurs if the ETC(electron transport chain) can occur and that is only with oxygen(and nothing keeping oxygen from binding such as cyanide).